As part of this master’s thesis, we investigated the effect of temperature on starch hydrolysis by endogenous enzymes in hydrated whole-grain flours from germinated and non-germinated wheat, spelt, and buckwheat grains. Hydrolysis was performed at 50–70 °C using a flour-to-water mass ratio of 1:2 and evaluated after 15 min, 2.5 h, and 18 h of incubation. Sugars and oligosaccharides were determined chromatographically, while reducing sugars were quantified spectrophotometrically using the dinitrosalicylic acid method. The extent of starch hydrolysis and the composition of the resulting sugars were significantly affected by flour type, germination, temperature, and incubation time. Maltose was the predominant hydrolysis product in wheat and spelt flours, whereas glucose predominated in buckwheat flours. Depending on the flour type, the optimal hydrolysis temperature was 60 or 65 °C. Hydrolysis generally increased with incubation time, whereas at 70 °C prolonged incubation caused no significant increase in most cases, indicating reduced activity or inactivation of endogenous enzymes. Germination increased starch hydrolysis in all investigated cereals and pseudocereals. The maximum degree of hydrolysis in wheat flour increased from 28 % to 32 % following germination. The effect was more pronounced in spelt flour, where hydrolysis increased from less than 15 % to 37 %, the highest value among the investigated samples. Buckwheat flours showed the lowest hydrolysis, reaching 4.3 % in non-germinated and 14.7 % in germinated samples. Changing the flour-to-water mass ratio from 1:2 to 1:1 or 1:3 had only a minor effect on starch hydrolysis in non-germinated wheat flour during longer incubation at 65 °C.
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